Haptoglobin (Hb) phenotyping was carried out in 143 patients with tuberculosis and 221 practically healthy persons. Three phenotypes were distinguished: two homozygotic Hp. 1:1 and Hp. 2:2 and one heterozygotic Hp. 2:1. An analysis of the frequency of distribution of the above-mentioned phenotypes indicates that patients with tuberculosis as compared with the healthy showed a significant reduction of the number of Hp. 2:1 carriers while the number of Hp. 2:2 increased. There was a definite dependence between the haptoglobin phenotype and course of the disease. In carriers of the Hp. 2:1 abacillation of the sputum and closure of destructions occurred earlier than in carriers of Hp 1:1 and, in particular, Hp. 2:2.